Evaluation of a Method to Detect Giardia and Cryptosporidium in Water

The current study outlines a technique to simultaneously detect Giardia and Cryptosporidium in raw and tap water samples. The influence of various procedural steps, including filtration, elution, flotation, filter mounting and microscopy, was determined for the method. Overall, the method recovered 48% to 69% of the Giardia and 25% to 42% of the Cryptosporidium in spiked water samples. The method had an averaged detection limit of 1 organism/100 L of tap water. Use of phase-contrast and Nomarski differential interference contrast microscopy could detect false-positive algal cells and determine cysts and oocysts having “non-viable type” morphologies.

LeChevallier, MW Research MicrobiologistResearch TechnicianDirector, American Water Works Service Company Inc., Belleville LaboratoryResearch for the American Water Works Service Company Inc., BellevilleVoorhees, ILNJ

Norton, WD Research MicrobiologistResearch TechnicianDirector, American Water Works Service Company Inc., Belleville LaboratoryResearch for the American Water Works Service Company Inc., BellevilleVoorhees, ILNJ

Lee, RG Research MicrobiologistResearch TechnicianDirector, American Water Works Service Company Inc., Belleville LaboratoryResearch for the American Water Works Service Company Inc., BellevilleVoorhees, ILNJ